Innova 8 seator is best bet for your requirment, Test drive Diesel (FE between 9-15kmpl) and Petrol (FE between 7-12kmpl) see which you like. For family use I suggest strictly 8 seator Innova rather 7 seator because 8 seator helps a lot when you need to carry kids
I suggest Innova V spec or G4.
Next comes Sumo Grande since you will be buying the vehicle in 6-7 months by that time i am sure Grande will be stable from initial glitches (assuming any new cars will heve one or other minor niggles) so its good one too.
Last choice is vehicle like Winger but its for taxy use rather than family use but you can check it out If you like it.
Regards,
Ravi.